Even a simple roof repair can seem needlessly expensive. With no moving parts or complex circuits, roof shingles seem like they should be simple and inexpensive to fix and even replace. While much of the work may be fairly straightforward, it still takes expertise and quality materials to finish a sturdy, safe and reliable roof. Materials, labor and insurance costs are the factors that drive roof repair prices through the roof.

Materials are Expensive

The price of asphalt shingles rose 58 percent from 2008 to 2009, and prices have continued increasing. This is partly due to the rising price of oil, though shingle prices are less likely to drop when the price of oil drops. The price of asphalt shingles is also affected by increasing demand for highway asphalt, thanks to all the stimulus-related road construction projects.

Asphalt shingles are by far the most common roofing material, but other materials also are getting more expensive. Lumber prices are on the rise, and plenty of quality wood is needed for rafters, trusses and other structural supports. Sheets of high-quality oriented strand board also are needed for the deck or sheathing.

Even the most basic materials add to the cost. Cheap staples don't cut it on a quality roof job. Galvanized steel roofing nails cost more, but must be used.

However, you can save on roofing materials with a $1,500 tax credit for certain qualified roofing materials. Also keep in mind that a more expensive but longer-lasting roofing material will save money in the long run.

Good Labor is Expensive

Of course, the best materials are only as good as their installation. A 40-year shingle could warp or leak after just months if improperly fastened.

Good roofing work is very precise. Insufficient overhang at the edge of the roof, for example, can lead to water damage. Too much overhang, however, can leave shingles weak and susceptible to damage.

Every job requires good workmanship, but some have less dire consequences. A sloppy paint job, for example, is just aesthetically unpleasing. A sloppy roofing job could lead to expensive leaks, poor ventilation, mold and even a hazardous collapse.

The best way to research a company's workmanship is by checking references and even inspecting previous jobs, if possible.

Insurance is Vital

Just as sloppy workmanship can have dangerous consequences on the roof, accidents on the roof can also be expensive - especially if you are liable. The lowest bidder likely doesn't pony up for comprehensive liability and workers' compensation insurance. Go with the higher bid and get proof of the proper insurance.

Insurance, workmanship and materials are the three main factors driving the cost of roof repairs and replacements through the roof.